Deep Love - Ayu no Monogatari

From Kotonoha:
Ayu, a 17-year-old high school student, believes neither in a future nor the happiness it could bring her. By selling herself, she tries to justify her existence, which is as bleak as her heart - it’s devoid of joy, sorrow, love. Not until her encounter with a kind-hearted old lady does Ayu begin to realize the true meaning of happiness…